Industrial process control and automation systems are often used to automate large and complex industrial processes. These types of systems routinely include sensors, actuators, and controllers. The controllers typically receive measurements from the sensors and generate control signals for the actuators.
Controllers and other devices in an industrial process control and automation system are typically connected to and communicate over one or more networks. Some devices in an industrial process control and automation system (such as more critical controllers) are arranged as redundant pairs, where one device in each pair operates in a primary role and another device in each pair operates in a secondary or redundant role. A secondary device is designed to switch into the primary role during a switchover, such as when the primary device suffers a power failure, hardware failure, or other problem.